Network redundancy ( failover )

I have instance set up to monitor our network, however It is on a sector that if the tower goes down, so will the internet access of LibreNMS. My box has another network plugged into it as well, that is not attached to our towers network. Is there a way that if the tower goes down LibreNMS can default to use the secondary connection so that it can still send alerts? Stupid question but is this something I need to enable in Libre or is this best to look at settings on the box to switch over?

This is more a linux question but that should be possible. You basically need to update the default route to point to the other interface.

Thank you for the insight and link. Very much appreciated.